Red Hat Bugzilla – Bug 1303728
Seeing VM crash while writing in same RBD Disk from different VMs
Last modified: 2017-07-30 11:36:16 EDT
Description of problem:
While trying to write on a same RBD image, the VM is getting crashed.
Version-Release number of selected component (if applicable):
rpm -qa | grep ceph
Selinux as enforcing.
Steps to Reproduce:
1. Create an rbd image with --feature 13, create snap and clone it.
2. Attach the same Clone to 2 different VMs.
3. Try to write on the RBD clone from 2 different VMs at same time
Used dd to write it.
Lock should handle this use case, and there should not be a crash
Seeing the VM Crash.
I discussed this with Jason and Josh, and the outcome is that we want to land a fix in 0.94.7 upstream and give it plenty of testing before pulling it downstream.
This is not technically a valid use case of RBD exclusive locking, and customers should never have two VMs using the same RBD image at the same time. If customers had such a setup, this would certainly cause other issues. Jason and Josh also confirmed that there's no way to hit this with a single client, nor during a VM live migration between hypervisors.
Since this is a lower priority bug, re-targeting to RHCS 1.3.3.
This was resolved in RHCS 2.x